DLC8023 Programming Interfaces

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The IEEE 802.3 Ethernet data link control (DLC8023) device manager conforms to generic data link control (GDLC) guidelines.

With the listed exceptions, the IEEE 802.3 Ethernet data link control (DLC8023) device manager conforms to generic data link control (GDLC) guidelines:

Note: The dlc prefix is replaced with the e3l prefix for the DLC8023 device manager.
Item Description
e3lclose DLC8023 is fully compatible with the dlcclose GDLC interface.
e3lconfig DLC8023 is fully compatible with the dlcconfig GDLC interface. No initialization parameters are required.
e3lmpx DLC8023 is fully compatible with the dlcmpx GDLC interface.
e3lopen DLC8023 is fully compatible with the dlcopen GDLC interface.
e3lread DLC8023 is compatible with the dlcread GDLC interface, under the following conditions:
  • The readx subroutines can have DLC8023 data link header information prefixed to the I-field. The data can be passed to the application in the user-defined readx subroutine data link header length extension parameter in the gdl_io_ext structure.
  • If this field has a nonzero value, DLC8023 copies the data link header and the I-field to user space and sets the actual length of the data link header in the length field.
  • If the field has a value of 0, no data link header information is copied. See the DLC8023 Frame Encapsulation figure (Figure 1) for more details.

The following kernel receive packet function handlers always have the DLC8023 data link header information in the communications memory buffer (mbuf), and can locate this information by subtracting the length passed in the gdl_io_ext structure from the data offset field.

Item Description
e3lselect DLC8023 is fully compatible with the dlcselect GDLC interface.
e3lwrite DLC8023 is compatible with the dlcwrite GDLC interface. The exceptions are that network data can only be written as an unnumbered information (UI) packet and must have the complete data link header prefixed. DLC8023 verifies that the local, or source, service access point (SAP) is enabled and that the control byte is UI (0x03). See the DLC8023 Frame Encapsulation figure (Figure 1) for more details.
e3lioctl DLC8023 is compatible with the dlcioctl GDLC interface, with conditions on the following operations: